to investigate the effect of mobile phone addiction with forward head posture on the endurance of deep neck flexor muscles, respiratory functions, pain pressure threshold , and neck functional disability level.

Nowadays, the mobile phone has become an important requirement. The number of mobile phone users and the duration of mobile phone use are increasing rapidly, and the side effects can be detrimental one of them is forward head posture.

Prolonged use of the mobile phone has also affected posture, resulting in many musculoskeletal disorders or improper posture. Neck posture, particularly in a sitting position, is regarded an essential contributing factor to the development and long-term maintenance of cervical pain and headache. Neck flexed posture increased due to the frequent use of the relatively small screen of a mobile phone compared to that of a desktop computer. Constant use may also have unexpected consequences: increased stress on the cervical spine.

Forward head posture (FHP) is the most common side effect of prolonged, sustained mobile and tablet use. This leads to extension at atlantooccipital (C1 to C2) joints with flexion of lower cervical spine (C4 to C7) and flattening of mid cervical lordosis which cause joint dysfunction associated with negative affection of lung function, abnormal afferent information affecting the tonic neck reflex and encourages the gradual adaptation of FHP.

Inclusion Criteria:

1. Forward head with craniovertebral angle less than 50 degree.
2. Both sexes will participate in this study.
3. Their age will be ranging from 18-40years (Molaeifar et al., 2021).
4. Body mass index is ranged from 18-25 kg /m2 (Molaeifar et al., 2021).
5. Area of mobile phone is 17 × 8cm.
6. Participants will be randomly allocated into 2 groups, group (A) should not have addicted to mobile phone and group (B) should have addicted to mobile phone.

Exclusion Criteria:

1. Previous cervical operation.
2. Musculoskeletal disorders such as cervical spine fracture, myelopathy, spinal cord tumor.
3. Neurological conditions that affected head, neck, and upper limbs.
4. Cervical disc or spondylosis.
5. Respiratory diseases such as Restrictions in lung function.

Adult both gender males and females, normal BMI, normal and forward head posture participants, addicted and not addicted to mobile phoine will be included in the study.